Catalytic removal of gas phase contaminants

Abstract

Systems and methods for removal of gas phase contaminants may utilize catalytic oxidation. For example, a method may include passing a gas that includes a gas phase contaminant through a catalytic membrane reactor at a temperature of about 150° C. to about 300° C., wherein the catalytic membrane reactor includes a bundle of tubular inorganic membranes, wherein each of the tubular inorganic membranes comprise a macroporous tubular substrate with an oxidative catalyst and a microporous layer disposed on a bore side of the macroporous tubular substrate, and wherein at least about 50% of the gas flows through the tubular inorganic membranes in a Knudsen flow regime; and oxidizing at least some of the gas phase contaminant with the oxidative catalyst layer, thereby reducing a concentration of the gas phase contaminant in the gas.

The invention claimed is: 
     
       1. A system comprising:
 a catalytic membrane reactor comprising a heating element in thermal communication with a bundle of tubular inorganic membranes and a housing having a gas inlet and a gas outlet and containing the bundle of tubular inorganic membranes, wherein the catalytic membrane reactor is configured such that, when in operation to catalytically remove gas phase contaminants from a gas, the gas flows, in order, into the housing through the gas inlet, into a bore of the tubular inorganic membranes, through a wall of the tubular inorganic membranes, and out of the housing through the gas outlet, wherein each of the tubular inorganic membranes comprise a macroporous tubular substrate with an oxidative catalyst and a microporous layer disposed on a bore side of the macroporous tubular substrate. 
 
     
     
       2. The system of  claim 1 , wherein the oxidative catalyst is impregnated in the microporous layer. 
     
     
       3. The system of  claim 1 , wherein the oxidative catalyst is in a layer disposed between the microporous layer and the macroporous tubular substrate. 
     
     
       4. The system of  claim 1 , wherein the microporous layer has a thickness of about 1 micron to about 10 microns. 
     
     
       5. The system of  claim 1 , wherein the microporous layer has a porosity of about 25% to about 50%. 
     
     
       6. The system of  claim 1 , wherein the microporous layer has an average pore size of about 4 nm to about 50 nm. 
     
     
       7. The system of  claim 1  further comprising:
 an adsorption bed upstream or downstream of the catalytic membrane reactor. 
 
     
     
       8. The system of  claim 1  further comprising:
 a photo-oxidation reactor upstream or downstream of the catalytic membrane reactor, the photo-oxidation reactor comprising a gas flow path and UV source arranged relative to the gas flow path to allow for UV irradiation of a gas contained in the gas flow path. 
 
     
     
       9. The system of  claim 8  further comprising:
 a particle filtration unit disposed downstream of the photo-oxidation reactor. 
 
     
     
       10. The system of  claim 1  further comprising:
 a selective surface flow reactor upstream or downstream of the catalytic membrane reactor. 
 
     
     
       11. The system of  claim 10  further comprising:
 an adsorption bed downstream of the catalytic membrane reactor and the selective surface flow reactor.